Printing machines or presses have a large number of rotating cylinders, rollers and other rotating mechanical components operating at high speed with mechanical bearings, bushings or the like that need lubrication. One common lubrication system employs an electrical control system for operating electro-magnetically operated valves to control the flow of grease to the points needing lubrication in a timed and controlled manner. These valves are called "inlet shunt valves", and they are solenoid operated valves which have solenoids electrically energized to shift the valves to an open or closed position. One particular lubrication system is a TRABON lubrication system that uses a solenoid shunt valve having an internal spool that is shifted to an open position by energization of the solenoid coil to allow grease to flow through the valve to the printing press lubrication points. An internal spring in the valve works in opposition to the solenoid and returns the valve to the closed position when the solenoid coil is de-energized. One such type of valve is called a "Lubriquip" shunt valve.
It has been found in use that these solenoid shunt valves were failing and causing the presses to be stopped with a consequent loss of press time. Also, the lubrication points were not being lubricated properly. The detection of a fault in the lubrication system also can and did cause "speed inhibits" faults that notified the operator to hold the presses down until the fault was cleared. Thus, there is a need for a new and improved grease shunt valve and system that has fewer problems. There may be as many as sixteen or more shunt valves on a single printing press. This represents sixteen opportunities during a press run for a detection of a fault in the lubrication system due to a faulty shunt valve.